To detect small quantities of mercury in water, atomic absorption spectrophotometry, ion chromatography, gas chromatography or mass spectrometry are typically used. These techniques require expensive equipment and high expertise, and cannot be done quickly, e.g. in minutes. A need exists for a rapid test for mercury that can be used by untrained personnel in the field, at industrial sites, or on the bench in analytical laboratories.
The Microtox.RTM. bacterial biosensor (Microbics Corporation) is used for detecting contaminants of an aqueous environment. Luminescence is inhibited by metal ions (Hg.sup.2+, Cu.sup.2+, Cr.sup.2+, Cd.sup.2+, etc) and organic compounds (sodium lauryl sulfate, formaldehyde, phenol, chloroform, etc) that decreases the metabolic processes of cells. This system is not contaminant specific. It merely indicates the presence of a material that adversely affect metabolism.
S. Frackman et al., J. Bacteriol., 172, 5767-5773, 1990, describe techniques for introducing genomic DNA fragments containing lux genes of Xenorhabdus luminescens into plasmids that are introduced into Escherichia coli by transformation. Insertion of lux operon fragments and of the complete lux operon into plasmid, the transformation of Escherichia coli by plasmid and aldehyde independent and dependent expression of the various lux gene fragments in E. coli are reported.
German Patent 3,902,902 discloses that suitably equipped organisms react specifically to the presence of Hg.sup.2+ by an increase in bioluminescence. A plasmid vector was prepared that contains "narrow spectrum" mercury sensing genes (parts of the mer operon originally from the E. coli mercury resistance plasmid R100) that can be induced by Hg.sup.2+ linked to genes for bacterial luciferase (luxAB) from Vibrio harveyi so that Hg.sup.2+ stimulates expression of the luxAB genes. Upon addition of a long-chain aldehyde, the microorganisms produce light. Microorganisms containing such plasmids can be used to specifically detect Hg.sup.2+ in water. This test requires the addition of aldehyde to produce bioluminescence.